The present invention is directed generally to electronic data transfer, and more particularly, to dynamic baselining in current modulation-based communication such as from a slave device in an electronic blasting system.
In the prior art electronic blasting systems, communication from slave detonators back to a blasting machine has been effected by voltage modulation from the detonator. The disadvantages associated with this include the necessity of having sufficient power in the detonator to drive the modulated voltages back to the blasting machine (resulting in increased power consumption and circuit complexity), and possible interference from environmental factors such as EMI, ESD, and/or RFI, which may impair proper data transmission.
While current modulation-based “talkback” from a slave device to a master device has been employed in other fields (typically with the master device holding the bus voltage high) such as RS-485, in electronic blasting systems (and certain other applications), noise presents a significant obstacle in that it interferes with the successful and accurate reception of data by the master device. For example, EMI, ESD, RFI, or intermittent wire leakage may impair data transmission integrity by varying the baseline of current of the talkback. The background current draw in such systems may also be particularly noisy when the bus voltage is high, because detonators may then be performing tasks such as active charging and/or charge-topping of firing capacitors, irregular current consumption of each detonator via charging of buffer capacitors, etc. Presumably for such reasons it has not been thought efficacious to employ current modulation-based talkback in an electronic detonator system, especially at high bus voltage.